Such a rail wheel is known from the literature and from practical application. Rubber-sprung rail wheels have been known for considerably more than half a century and have a successful track record in practical application. In a rubber-sprung rail wheel of which hundreds of thousands have been in use, the rubber insert comprises a plurality of radially highly prestressed rubber pads that are seated in facing annular grooves of the wheel tire and of the wheel rim. When compared to such a rail vehicle wheel, the rail vehicle wheel of the type mentioned in the introduction, which rail vehicle wheel comprises the differently oriented and axially prestressed rubber insert, provides the advantage of greater axial rigidity when subjected to lateral loads such as driving along a curved section of track, and of a lower spring constant when subjected to vertical loads. However, this arrangement is associated with a disadvantage in that when subjected to vertical loads the rubber insert is essentially subjected to shear stress.
In order to be able to cope with such high shear loads, attempts have been made to use the greatest possible volume of rubber and to provide the rubber insert with very considerable axial prestress. In order to generate the very considerable axial prestress, the flanges that rim the rubber insert on the outside are braced to each other by means of screw bolts that lead through the flanges, the rubber insert and the web. While in this way even axial prestress in the rubber insert can be achieved over the diameter, this type of bracing is, however, associated with a loss of rubber volume. However, in various applications, in particular in the case of low-floor carriages, where comparatively small wheel diameters are required, it is not possible to provide a larger radial area in order to accommodate more rubber volume.
From DE 44 30 342 A1 a rubber-sprung rail wheel is known that comprises a wheel rim, a wheel tire and annular rubber inserts. They are exclusively held on both sides of the mid-plane of the wheel in annular spaces that are formed by a web that protrudes radially inwards from the wheel tire, and by flanges that correspondingly protrude radially outwards from the wheel rim, under essentially axial prestress exclusively between supporting surfaces of the web and of the flanges. While one flange is constructed in one piece with the wheel rim body, the other flange with an integrally formed annular joined-on piece of rectangular cross section is placed in a corresponding annular recess that is provided in the wheel rim body and, by means of a screw connection, is directly connected to the wheel rim body, wherein the annular joined-on piece and the annular recess form a cylindrical seat. In this arrangement the axial prestress of the rubber inserts is entirely produced by the screw connection. In order to evenly prestress the rubber inserts across their radial width, a correspondingly rigid construction of flanges and screw connections is required.
In a different type of rubber-sprung rail wheel, known from DE 24 06 206 C3, the annular rubber inserts are held under axial and radial prestress between a cylindrical and a radial supporting surface of a wheel rim ring and a radial supporting surface of a wheel disc on the one hand, and the essentially radial supporting surfaces of a middle web and the flanks of the wheel tire, which flanks are arranged immediately adjacent to said middle web and are essentially cylindrical, on the other hand. In this arrangement the radially slotted wheel rim ring with a conical seat surface rests against a corresponding conical supporting surface of the wheel disc, and is connected to it by way of screw bolts that are arranged outside the rubber insert. As a result of the inclination of the conical surfaces a self-locking seat of the wheel rim ring on the wheel disc is achieved, which wheel rim ring due to the radial slit in the diameter is radially expandable. As a result of this seat, the screw bolts are relieved by the restoring forces of the prestressed rubber insert.